HR: 09:10h
AN: SH31B-05    [Abstracts]
TI: Rapid directional alignment of velocity and magnetic field in magnetohydrodynamic turbulence
AU: * Matthaeus, W
EM: whm@udel.edu
AF: Bartol Research Institute and Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19711, United States
AU: Pouquet, A
EM: pouquet@ucar.edu
AF: NCAR, P.O. Box 3000, Boulder, CO 80307-3000, United States
AU: Mininni, P
EM: mininni@df.uba.ar
AF: NCAR, P.O. Box 3000, Boulder, CO 80307-3000, United States
AU: Dmitruk, P
EM: pablo@bartol.udel.edu
AF: Departamento de Fi sica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires Ciudad Universitaria, Buenos Aires, 1428, Argentina
AU: Breech, B
EM: breech@cis.udel.edu
AF: Bartol Research Institute and Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19711, United States
AB: We show that local directional alignment of the velocity and magnetic field fluctuations occurs rapidly in magnetohydrodynamics for a variety of parameters. The phenomenon, which occurs within an eddy turnover time regardless of the initial alignment of the fluctuations, is observed both in direct numerical simulations and in solar wind data. The phenomenon is due to either pressure gradients or shear-associated kinetic energy gradients acting along the magnetic field. A similar alignment, of velocity and vorticity, occurs in the Navier Stokes fluid case. This may be the most rapid and robust relaxation process in turbulent flows, and leads to a local weakening of the nonlinear terms in the small scale vorticity and current structures where alignment takes place.
DE: 2149 MHD waves and turbulence (2752, 6050, 7836)
DE: 7863 Turbulence (4490)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting